This Week in HIV Research: Another Notch in the 'Treatment as Prevention' Belt

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Despite the extensive knowledge we've gained over the years about HIV, there's always so much more to learn about HIV transmission, pathogenesis, treatment, and care management. This week, our selected studies teach us that:

  • Evidence keeps on piling up in support of U=U (undetectable equals transmittable), particularly among men who have sex with men.
  • Sex workers in Africa may benefit from enhanced HIV prevention and treatment interventions, but not necessarily from a viral suppression standpoint.
  • People living with HIV who make it two years without leaving care are much more likely to re-engage in the future if they ever drop out of the care continuum.
  • Thyroid function appears no different for HIV-positive people on effective treatment than HIV-negative people.

Come learn more about each of these study results in the following pages. To beat HIV, you have to follow the science!

Barbara Jungwirth is a freelance writer and translator based in New York. Follow Barbara on Twitter: @reliabletran.

Myles Helfand is the executive editor and general manager of and Follow Myles on Twitter: @MylesatTheBody.

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Another Study Finds Zero HIV Transmissions in MSM With Virally Suppressed Partner

No HIV transmissions within serodiscordant male couples were reported in a multinational study that focused on condomless anal intercourse (CLAI) and was published in The Lancet. The results of this study, Opposites Attract, mirror those from the larger PARTNER2 study presented at the 22nd International AIDS Conference last month.

The three seroconversions that did occur during the study, which followed 343 couples in Australia, Brazil, and Thailand for an average of one to three years per couple, were not phylogenetically linked to the partner's virus -- i.e., HIV had been acquired outside the primary relationship. Excluding periods when the partner living with HIV was not virally suppressed or the HIV-negative partner was taking pre-exposure prophylaxis (PrEP), researchers calculated a maximum HIV transmission rate of 1.59 per 100 couple-years, or less than 2% chance of seroconversion. If PrEP or condoms were used, or the partner living with HIV was virally suppressed, the calculated maximum transmission rate dropped to 0.63 per 100 couple-years.

While the PARTNER2 results presented at the recent 22nd International AIDS Conference by Alison Rodger, M.D., concluded that there was no transmission risk at all, the Opposites Attract researchers were a bit more cautious, calling the risk "very low," not none. However, the authors -- whose study results were submitted for publication prior to the PARTNER2 presentation -- noted that additional, longer-term data would make it possible to assert with greater confidence that treatment as prevention was extremely effective among men who have sex with men (MSM).

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Mixed Results From Enhanced HIV Interventions Among Sex Workers in Zimbabwe

An enhanced prevention and treatment intervention for women who are sex workers in Zimbabwe did not greatly affect the number of participants with high viral loads, a study published in The Lancet found.

In the study, 8,231 women attending clinics for sex workers were randomized to receive either the usual care or the enhanced intervention. The proportion of participants with a viral load over 1,000 copies/mL fell from 30% in both groups to 19% in the usual-care group and 16% in the intervention arm. However, twice as many women in the intervention group were tested for HIV than in the control group (2,606 vs. 1,151). Similarly, 1,052 women were diagnosed with HIV in the intervention arm compared to 546 such diagnoses in the usual-care arm.

In a related commentary, Katrina Ortblad of Harvard and Catherine Oldenburg of the University of California-San Francisco pointed out that even the "usual care" group received sexual health services beyond those generally available to sex workers in sub-Saharan Africa. Thus, engagement in care may have already been relatively high in both groups, which could account for the lack of difference in reducing viral load. Sex workers are a diverse demographic, and combination approaches tailored to specific subgroups are needed to reduce HIV transmission, the comment authors argued.

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Two-Year Mark May Be Turning Point for HIV Care Engagement

People living with HIV who drop out of care within two years of starting it are less likely to re-engage than those who remained in care for at least two years, a longitudinal data analysis published in AIDS found. Other factors contributing to disengagement were: not starting antiretroviral therapy, having lower CD4 counts, having higher viral loads, and not having an AIDS-defining illness.

Researchers used data on 31,009 people living with HIV in the U.S. between 1996 and 2014. Results show that scaling up a test-and-treat strategy not only enhances HIV prevention and treatment, but also helps to retain people in care, study authors concluded.

The authors cautioned that the data did not allow controls for substance abuse, depression or insurance status -- all factors that may affect retention in care. However, the study's approach to data analysis could be used to develop algorithms that predict who might be at greater risk of dropping out of care, the researchers said. Tailored interventions could then be used to retain these people in care, they added.

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No Greater Risk of Thyroid Dysfunction If HIV Is Well-Treated

Thyroid function is not affected by HIV in people whose virus is well controlled, a Danish study published in AIDS showed.

Mild iodine deficiency, which can impair thyroid function, is common in the Copenhagen region, where researchers measured markers for thyroid function in 826 people living with HIV and 2,503 matched HIV-negative controls. Over 95% of participants living with HIV (PLWH) had undetectable viral loads.

Hypothyroidism was detected in 3.8% of PLWH and 4.6% of controls (not a statistically significant difference), and hyperthyroidism in 0.8% in either group. Serum concentrations of thyroid stimulating hormone also did not differ by HIV status. Similarly, CD4 cell count, CD4 nadir, and time since HIV was acquired were not associated with prevalence of thyroid dysfunction.

Before the advent of combination antiretroviral therapy, thyroid problems were common among PLWH. The results show that this no longer appears to be the case in PLWH with well-controlled virus.